It is well known to use inflatable bodies as weight supporting structures such as for air mattresses used by campers and backpackers. Inflatable structural shapes are also known which have opposed sheets of an air impervious envelope fastened together by a plurality of threads extending across the air space, with the threads woven into the fabric of the airtight envelope. Structural shapes of this description are shown in U.S. Pat. No. 3,138,506. Inflatable air mattress structures having a flexible foam core enclosed within and adhered to an airtight flexible jacket are shown in U.S. Pat. Nos. 3,872,525; 4,025,974; 4,149,919; 4,261,776; and 4,624,877. These patents, while showing a relatively lightweight air mattress, teach devices which must include a foam core which inherently adds appreciably to the weight of the device, a serious detriment for backpackers. In addition, the cost of the foam core contributes significantly to the cost of the device.